Statistically, it is assumed that 0.1% to 0.2% per population corresponds to is profound hearing loss that cannot be heard, 1% to 2% per population corresponds to moderate and severe hearing loss, and 10% to 15% corresponds to mild hearing loss. People corresponding to the range of the mild hearing loss have a difficulty in hearing a sound of 20 dB to 40 dB but can make conversation with another people close to them without difficulty. Therefore, most of the people corresponding to the range of the mild hearing loss rarely go to hospital because they do not recognize seriousness of their hearing loss. However, if the people corresponding to the range of the mild hearing loss continuously use an audio player with excessively great volume, their hearing loss may become the moderate hearing loss. In worst case, their hearing loss may become the severe hearing loss or the profound hearing loss.
In modern society, many people use various audio players, such as TV, the AM-FM Radio, CD player, MP3 player, audio cassette, PC, and language player.
The audio players currently selling in the market have a volume amplifying function enough to cause hearing loss. Since most of users of the audio players tend to listen to music with high volume, their hearing loss becomes serious to cause the mild hearing loss. Particularly, since people who much like music tend to listen to music with high volume, those people are more serious in hearing loss to cause moderate hearing loss or profound hearing loss.
The related art audio player has caused more serious hearing loss because it played audio regardless of individual audiogram.
Auditory cells of a cochlear canal have frequency bands and volume, which are determined. Audiogram is a distribution of sense per frequency of the auditory cells, which is obtained by hearing test. People have unique audiogram like fingerprint or DNA structure. Such audiogram may be varied due to aging or excessive great volume. For example, supposing that anyone listened to a sound of a frequency of 1 kHz at the intensity of 80 dBHL or greater for several hours, its particular auditory cell that handles the sound of 1 kHz is exposed to an excessive sound, thereby causing sudden hearing loss. Supposing that anyone who likes a sharp and stimulus sound repeatedly listens to a sound of a frequency of 10 kHz with high volume, its hearing may cause a functional hearing loss for the frequency band of 10 kHz.
Meanwhile, FIG. 1 illustrates the result of volume control of the related art audio player. In FIG. 1, a first group 100 and a second group 102 are shown. The first group 100 has a threshold of 0 dBHL around 1 kHz in an outer hair cell group while the second group 102 has a threshold of 30 dBHL.
Since the related art audio player linearly controls volume, it is likely that the first group 100 may be damaged. In other words, if volume is controlled at 90 dBHL, the second group 102 may feel less fatigue because it is exposed at 60 dBHL. However, the first group 100 may be damaged due to volume distortion and fatigue because it is overexposed at 90 dBHL.
To avoid loss of the auditory cells, which may be caused by linear volume control of the audio player, equalization may be performed to enable individual volume control per frequency band.
Generally, an equalizer allows a user to listen to music at a desired sound tone. For example, anyone who likes a clear and elegant sound can volume the high frequency band of the equalizer up to listen to a desired sound. Anyone who likes a magnificent and powerful sound can volume the low frequency band of the equalizer up to listen to a desired sound.
In addition to making user's desired sound tone, the equalizer is used for medical treatment such as an aural aid and an artificial cochlear canal.
In case of hearing loss patients who need an aural aid or an artificial cochlear canal, the equalizer should essentially be controlled depending on their audiogram after testing their hearing per frequency. This is because that hearing becomes worse if a hearing loss patient having no great hearing loss for a frequency band of 10 kHz is supplied with a sound through an aural aid and an artificial cochlear canal that did not perform equalization (referred to as “fitting” in acoustics) for a frequency band of 10 kHz.
However, if it is intended to provide an audio player based on audiogram of a user using the equalizer, it is difficult to provide such an audio player according to an equalization method based on audiogram in the existing audiogram test method.
In the related art audiogram test method, a particular frequency band is selected by manipulation of a tester based on six frequency bands of 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz. Afterwards, the intensity of a test sound is manually controlled to determine an auditory threshold in the particular frequency band. In this way, another frequency band is selected to determine its auditory threshold.
In other words, in the related art audiogram test method, since the step of selecting a frequency of the tester, the step of suggesting a test sound, and the step of determining the auditory threshold depending on response of the test sound of a testee are separately performed, maximum time as much as 50 minutes is required to determine the auditory threshold in six frequency bands as above. Therefore, if the related art audiogram test method is applied to the audio player, it is difficult for the user to select the frequency of the audio player, receive the test sound, and determine the auditory threshold.
Particularly, time required for testing the auditory threshold becomes long as a frequency band is subdivided. Therefore, it is difficult to provide the audio player in which equalization is performed based on the related art audiogram test method.
Furthermore, if the test sound is provided by controlling the intensity only in a state that a particular frequency is selected, a test error may greatly occur due to adaptation and selective attention of the user, thereby making exact audiogram test difficult.